Factors influencing susceptibility and resistance of mosquitoes to dengue viruses will be studied. Selection experiments will be carried out in an attempt to breed genetically pure lines of Aedes albopictus which are resistant and susceptible to infection with dengue. The genetic basis of resistance will be studied in these pure lines. Growth and distribution of dengue viruses in resistant and susceptible mosquitoes will be studied in an attempt to identify the physiological basis of resistance.